Sucrose Active Transport and Fermentation by Saccharomyces cerevisiae

摘要

Sucrose is the major carbon source used by Saccharomyces cerevisiae during production of fuel ethanol, baker s yeast, and several distilled beverages. In the present work we analyzed the contribution to sucrose fermentation of a poorly characterized pathway of sucrose utilization by S. cerevisiae cells, the active transport of the sugar through the plasma membrane and its intracellular hydrolysis. Our results show that a yeast strain lacking the enzyme invertase ferments sucrose efficiently due to direct uptake of the sugar into the cells, with no glucose or fructose being produced in the medium during sucrose fermentation. Furthermore, a yeast strain that lacks the major hexose transporters (hxt1-hxt7 and gal2), and thus incapable of growing on orfermenting glucose or fructose, also ferments sucrose efficiently. The molecular characterization of active sucrose transport and fermentation by S. cerevisiae cells opens new opportunities to optimize yeasts for sugarcane-based industrial processes.